Simulating dendrite formation on Lithium metal anode.

P. V. SARAVIA; G. PEÑARANDA; ANDREA C. CALDERÓN; E. P. M. LEIVA; PAZ S. ALEXIS

Buenos Aires

Congreso; HYCELTEC: 8th Symposium on Hydrogen, Fuel Cells and Advanced Batteries; 2022

Lithium metal is considered the ultimate anode for energy-storage systems for its extremely high theoretical specific capacity (3860 mAh g−1), the lowest redox potential (−3.040 V vs the standard hydrogen electrode) and a low gravimetric density (0.534 g cm−3) [1]. However, the main issue associated with this electrode is the growth of metal dendrites on its surface, also known as high surface area lithium (HSAL), during charge/discharge cycles. Therefore, there is a great interest in the study of the mechanism of HSAL formation and the effect of the different variables involved. A final goal is the possibility to tune these variables to control the formation of HSAL. Such control remains elusive probably because it requires important feedback between theory and experiments, among other challenges. Molecular simulations could help to improve this feedback, although the construction of an ad hoc model that connects the simulation parameters with the experimental measures is required. In this work, we have developed a computational model, based on that of Mayers et al. [2], to simulate the HSAL growth on a planar electrode.Since the electrode works by draining lithium particles from the SEI during electrodeposition, new particles must be added to the system (where thermodynamical properties are calculated, in the μVT thermodynamic ensemble) during the progress of the simulation. A direct way to accomplish such additions is the definition of a local control volume in the simulation box, where new particles will be created. The number of particles inside this reservoir will be related to the chemical potential, and can be controlled using any grand canonical simulation method. Usually, the output properties of the simulation are measured far from the reservoir, with the hope to avoid any perturbation to the system given by its presence. However, we show that it is not possible to uncouple the system from the reservoir in the regime of deposition at high potentials, since the concentration profiles will quickly reach the reservoir position, no matter how far it is located.